Currently, public transit vehicle manufacturers use finite element analysis (FEA) and road testing to verify the structural integrity of their vehicles during the design and testing phases of vehicle development. However, such testing does not always accurately reflect the conditions actually encountered by particular vehicles in service. For example, one major unknown factor in structural design integrity is the conditions of the streets on the routes actually taken by any given bus(es) in service.
Sometimes, vehicles are driven over test routes intended to simulate service conditions. Such vehicles may be instrumented with strain gauges at critical joints, and driven on “typical” transit, commuter, or other routes, so that allegedly representative data may be gathered and analysed. One concern is whether the chosen test site, route and driving conditions are in fact representative of the operating environments to be experienced by all relevant individual vehicles in service. Also, data can be skewed by such factors as the time of year, the individual driver(s) used to conduct the test, and whether or not a test route has been recently resurfaced or otherwise maintained, or is nearing the end of its useful life. As a result, simulation of real-life duty cycles by the best available and most sophisticated techniques can be in error by wide margins (for example, 50%-100%, or more).